1. Field of the Invention
The invention relates to the field of implantable cardiac stimulation devices and to improved systems and methods of adjusting implantable devices for individual patients.
2. Description of the Related Art
Numerous patients suffer from disease conditions that affect their cardiac performance. For example, diseased myocardium reduces the mechanical pumping capabilities of the heart. Impaired conduction and/or abnormalities in intrinsic activation can result in inappropriate/impaired stimulation of the cardiac tissue.
Implantable cardiac stimulation devices have been developed to provide therapy for at least some patients suffering impaired cardiac function. Implantable cardiac stimulation devices generally include an implantable stimulation pulse generator and a microprocessor based controller regulating operation of the device. Implantable cardiac stimulation devices also typically include one or more implantable leads which are configured for implantation to extend adjacent the patient's heart. The implantable leads typically include one or more electrodes. The electrodes can be configured for dedicated sensing or delivery of stimulation or can be configured for combined sensing and stimulation delivery functions. The implantable devices are generally adapted to automatically sense the patient's status and automatically generate and deliver stimulation for cardiac abnormalities.
One particular category of implantable cardiac stimulation devices are capable of what is generally known as cardiac resynchronization therapy (CRT). CRT capable devices include leads adapted for delivery of therapeutic stimulation to multiple chambers of the patient's heart, such as to the left and right ventricles. CRT devices attempt to improve pumping efficiency of the patient's heart by providing therapeutic stimulation to improve relative synchrony of operation, e.g., contraction/relaxation, between multiple chambers of the patient's heart. For at least certain patient's, CRT can significantly improve an impaired cardiac output and provide corresponding improvements in quality of life.
An expanding patient population with unhealthful lifestyle histories and/or predisposition to cardiac abnormalities contributes to an ever-increasing patient population with impaired cardiac function. Ongoing developments in therapeutic device design provide increased capabilities for the devices thereby expanding the proportion of the patient population that can benefit from therapies available with the devices. The combination of an increasing population in need of cardiac therapy with therapeutic devices capable of providing an increasing variety of therapies results in an increasing number of matches between patients having need of therapy and therapy devices capable of addressing that need.
While this has obvious benefits to public health, there remains a significant burden on attending clinicians in providing appropriate therapy to the individual patients. Implantable cardiac stimulation devices generally include a variety of operational parameters that are preferably adjusted for the particular needs and condition of a given patient. While these variable parameters can be preset, for example to an average setting, in many applications it is preferred that the device as implanted in the patient be evaluated and the operational parameters be adjusted for improved performance in that individual patient.
Accordingly, implantable cardiac stimulation devices are frequently provided with the ability to telemetrically communicate with an external device, such as a physician's programmer. The physician's programmer allows a clinician to communicate with the therapeutic device in the implanted state at time of implantation as well as subsequently during follow-up visits. Such implantable stimulation devices and physicians programmers share bidirectional communication such that the implantable device can upload data to the physician's programmer, such as operational status information and historical data. The physician's programmer can provide commands to the implanted device, for example to adjust the device programming. This allows a skilled clinician to evaluate the operation of the device in the implanted environment and make any indicated adjustments in the device's programming to improve the delivery of therapy to the patient.
While this improves delivery of therapy to the patient, it places a significant burden on the attending clinicians to individualize or optimize the programming of an implantable device with the unique needs and conditions of an individual patient. As devices become more complex with increased capabilities, there is a tendency for an increasing number of parameters that can be individually adjusted for a given patient. Evaluating even a limited number of different combinations of variable parameters with the time needed for designating changes between the different combinations and for the changes to take effect for evaluation can require a significant amount of time from the highly trained and skilled clinician. Thus, it will be appreciated that reducing the burden on highly trained and skilled clinicians in adjusting a therapeutic device for the needs of an individual patient while maintaining the benefits of improvements in available therapeutic systems would be highly desired.
A further issue in adjusting an implantable therapeutic device for treatment of an individual patient is that a patient's condition can be subject to change over time. For example, a patient's condition may deteriorate indicating an adjustment in their therapy regimen. Similarly, a patient's condition can improve such that previously provided therapeutic parameters are no longer appropriate for the approved condition. For example, a patient provided with CRT may positively respond in a phenomena sometimes known as remodeling thereby indicating changes in their therapy. Secondary factors, such as diet, lifestyle, and/or medications can also alter the patient's condition on both short term and long term basis. Thus, at least certain patients are scheduled for follow up clinical visits wherein a clinician reevaluates the patient's condition and may adjust the operating parameters of the device via telemetric interrogation with assistance of a physician's programmer.
Thus, it will be appreciated that there is a need in at least certain applications for ongoing monitoring and possible reprogramming of an implantable therapeutic device throughout an implantation period. There exists a similar need to reduce time burdens and inconvenience on the clinician and the treated patient to perform these follow up evaluations and possible readjustments. It would also be advantageous to provide the ability to more timely adjust operating programming of an implantable device closer in time to changes in the patient's condition indicating such readjustment rather than waiting for a follow up clinical visit.